Sstrhsrtj

I have a table with data from a file and before anything, I sort the data. Then I would like to filter only the rows that have a specific value. There has been a similar question which almost contains the answer to my question:

Selecting rows to be displayed with pgfplotstable

In addition to that I would like to know how to plot the filtered data.

Here is an example:

documentclass{minimal}

usepackage{pgfplotstable} 

usepackage{pgfplots}   



begin{document}

pgfplotstableread{

T   A   B   C

20  0   450 43

23  0   400 42

25  0   350 41

30  0   320 40

40  0   300 40

20  10  400 38

23  10  380 37

25  10  350 36

30  10  310 35

40  10  280 34

}data



pgfplotstablesort[sort key={T}]{sorted}{data} %get the data and sort by column 'T'



   %select data in column 'T' that complies with a certain value and write the table

   pgfplotstabletypeset[row predicate/.code={%

   pgfplotstablegetelem{#1}{T}of{sorted}

   ifnumpgfplotsretval=20relax

   elsepgfplotstableuserowfalsefi}]

   {sorted}



   begin{tikzpicture}

    begin{axis}[

     xlabel=A,

     ylabel=B]

   addplot table[

    x=A,

    y=B]

   {filtered}; %here the filtered data from above needs to be addressed, how to do that?

   end{axis}

   end{tikzpicture}



   end{document}

What I don't know is how to address the filtered data above to plot it. I thought it might work by generating a table named filtered.

You can use the x filter/.code={} instructions (thanks to Jake for spotting a mistake)

documentclass{minimal}

usepackage{pgfplotstable} 

usepackage{pgfplots}   



begin{document}

pgfplotstableread{

T   A   B   C

20  0   450 43

23  0   400 42

25  0   350 41

30  0   320 40

40  0   300 40

20  10  400 38

23  10  380 37

25  10  350 36

30  10  310 35

40  10  280 34

}data



pgfplotstablesort[sort key={T}]{sorted}{data}



   pgfplotstabletypeset[row predicate/.code={%

   pgfplotstablegetelem{#1}{T}of{sorted}

   ifnumpgfplotsretval=20relax

   elsepgfplotstableuserowfalsefi}]

   {sorted}





   begin{tikzpicture}

    begin{axis}[

     xlabel=A,

     ylabel=B,

    x filter/.code={pgfplotstablegetelem{coordindex}{T}of{sorted}

                    ifnumpgfplotsretval=20

                    else

                    defpgfmathresult{}

                    fi

                   },

    ]

   addplot[only marks] table[x=A,y=B] {sorted};

   end{axis}

   end{tikzpicture}

   end{document}

If the entries of the table involves nonintegers then ifnum would complain hence it needs another step.

documentclass{minimal}

usepackage{pgfplotstable} 

usepackage{pgfplots}   



begin{document}

pgfplotstableread{

T   A   B   C

0.567641034 0.111435797 0.886143166 0.536835288

0.919931469 0.702921973 0.285814111 0.796042178

0.073058973 0.921420655 0.806947507 0.570962079

0.697073289 0.017461888 0.313614435 0.905702895

0.536575411 0.814853755 0.152870278 0.556116015

0.574615343 0.162798271 0.553041948 0.605668041

0.567641034 0.248224272 0.448683336 0.092672169

0.117628849 0.115555917 0.193712749 0.561100742

0.625852254 0.993854404 0.950034992 0.595500664

0.975451837 0.152198913 0.647432196 0.790471281

0.692695418 0.099750965 0.122178502 0.141174403

0.106974613 0.905644903 0.491119067 0.795346

0.727907584 0.408384001 0.586645737 0.172061294

}data



pgfplotstablesort[sort key={T}]{sorted}{data}







   begin{tikzpicture}

    begin{axis}[

     xlabel=A,

     ylabel=B,

    x filter/.code={pgfplotstablegetelem{coordindex}{T}of{sorted}

                    pgfmathtruncatemacro{tempva}{abs(pgfplotsretval - 0.567641034) == 0 ? 1: 0}

                    ifnumtempva>0%true

                    else%false

                    defpgfmathresult{}

                    fi

                   },

    ]

   addplot[only marks] table[x=A,y=B] {sorted};

   end{axis}

   end{tikzpicture}

   end{document}

which leads to the same output above. I have modified a table entry as it is almost passing the test if lowered slightly. So you should be careful about the numerical precision.